The present invention relates to a protocol negotiations mechanism that allows a facsimile transmission between two systems. More particularly, the present invention relates to using a synthesized packet to negotiate transmission protocols between two voice over packet systems.
Developments in router technology have led to system designs that provide a general-purpose connection-oriented transfer mode for a wide range of services. These services include the simultaneous transfer of integrated traffic (data, voice, and video traffic) over the same network system. Typically, in the prior art, a voice over packet system (xe2x80x9cVOPSxe2x80x9d) is used as an interface between the network system and the devices that generate data, voice, or video traffic. The VOPS provides a digital signal processor (xe2x80x9cDSPxe2x80x9d) to convert data between analog signals and digital signals prior to data transmission over the network system. The VOPS also provides multiple code/decode (xe2x80x9ccodecxe2x80x9d) devices to both compress data prior to transmission and decompress received data, thus reducing data congestion over the network system.
FIG. 1 shows a prior art voice over packet network system. In particular, system 100 includes a voice over packet system (xe2x80x9cVOPSxe2x80x9d) 120 coupled to network 130 via an input/output serial line (161). Network 130 typically includes either a Frame Relay network, an Asynchronous Transfer Mode (xe2x80x9cATMxe2x80x9d) network, a High-level Data Link Control (xe2x80x9cHDLCxe2x80x9d) network, or and Internet Protocol (xe2x80x9cIPxe2x80x9d) network. Network 130 provides a transmission media between VOPS 120, node 140, and node 150.
As illustrated in FIG. 1, VOPS 120 includes a phone (110) and a facsimile (115) connected to a physical port (105). Physical port 105, in turn, is coupled to a DSP (125) and a codec bank (135). Codec bank 135 includes a group of codec devices (C1, C2, C3, and C4) that determine the transmission and compression protocol performed by DSP 125. For example, codec C1 includes a G.729 compression algorithm that compresses a 64,000 bits (i.e. 64K) voice call into an eight thousand bits compressed data stream. Thus, to maintain a voice call from phone 110 to phone 145 of node 140, DSP 125 uses the compression algorithm in codec C1 to generate a digital stream that is packetized and transmitted across network 130. Subsequently, the digital data is decompressed and reconstructed as analog signal by a DSP device included in node 140. The analog signal is transferred to phone 145. The data decompression performed by the DSP of node 140 is possible because the G.729 is an industry standard used to compress/decompress voice data.
Following the previous example, a data transmission from facsimile 115 to node 140 may require that DSP 125 uses a facsimile image algorithm located in codec C2. Provided node 140 supports the facsimile image algorithm of codec C2, a facsimile transmission between VOPS 120 and node 140 is possible. If the facsimile image algorithm of coded C2 is not supported by node 140, however, the data transmission from facsimile 115 to node 140 may fail. Thus, system 100 results in numerous disadvantages when used in a heterogeneous networking system that supports multiple codec devices between different nodes. One disadvantage results from the inability to transmit facsimile data that does not follow an industry standard codec algorithm. Another disadvantage results from the inability to transmit data between multiple voice over packet systems that prioritize transmission protocols differently. Yet another disadvantage results from the inability to transmit facsimile data between a VOPS that supports a propriety transmission protocol to a VOPS that supports a non-propriety protocol.
It is therefore an object of the invention to provide a protocol negotiations mechanism that allows a facsimile transmission between a voice over packet system (xe2x80x9cVOPSxe2x80x9d) and a remote VOPS.
It is a further object of the invention to provide a VOPS that comprises a table with supported codec algorithms. The supported codec algorithms are used to facilitate protocol negotiations between the VOPS and a remote VOPS.
It is a further object of the invention to provide a VOPS that transmits a switchover facsimile packet to facilitate protocol negotiations between the VOPS and a remote VOPS.
These and other objects of the invention are provide by a method for selecting a transmission protocol for a voice over packet system (VOPS). The method comprises generating a first data comprising a plurality of transmission protocols. For one embodiment, the VOPS is operable to receive data using the plurality of transmission protocols. The method also comprises transmitting the first data to a remote VOPS. Additionally, the method comprises receiving a second data from the remote VOPS. The second data selects at least one of the plurality of transmission protocols. For another embodiment, the remote VOPS transmits data to the VOPS according to one of the selected plurality of transmission protocols.
Other objects, features, and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description that follows.